I should distinguish between a bookmark and a post in Connotea terminology. A bookmark is a URL along with corresponding metadata, such as the title and md5 hash of the URL. A post represents an event: the adding of a bookmark to a specific user’s library. Accordingly, a post contains metadata about the name of the user, the tags the user has assigned to the bookmark, and the date of the event. A bookmark may belong to many users, but a post is tied to one and only one user. You can access the bookmarks in a given user’s library here:

http://www.connotea.org/user/{user}

For example, you can find the bookmarks of Timo Hannay, the publishing director of Nature.com, here:

There are some major conceptual similarities between the Connotea API and the del.icio.us API. For instance, both require authentication. However, in the Connotea API, you can access other users’ posts.

To see whether the Connotea API recognizes your username/password combination, issue the following request:

You can compare how a given URL is described as a bookmark and as a post in the two calls to see the differences between what posts and bookmarks are. A bookmark contains information about a given URI, its title, and which users have included (or “posted”) it into their own libraries: